Disk changers and other optical disk systems allow a disk to be selected and moved into or out of a read unit or read/write unit for access to the contents of the disk. Multiple disks may be in one or more magazines or cartridges, or available as bare disks on a tray, in a carousel or other arrangement.
Typically, a read unit or read/write unit may allow a single disk to pass through a single disk entry/exit slot or aperture. Likewise, a magazine or cartridge typically has a single disk entry/exit slot or aperture through which a disk may be put into or taken out of the magazine or cartridge.
When moving an optical disk from one location to a read or read/write unit, an optical disk transport mechanism may be used. A flat, carousel-based disk changer usually rotates the carousel to bring a disk to a read/write head. A toroidal array, carousel-based disk changer usually rotates the carousel to bring a disk to a read/write unit, and an additional mechanism moves the disk into the unit. These carousel-based disk changers move the entire optical disk array as part of an optical disk transport mechanism.
Other systems may use an optical disk transport mechanism to select a disk and bring the disk to or from a read unit or read/write unit without moving the entire optical disk array.
A read unit or a read/write unit often employs a roller to roll a disk into or out of the read or read/write unit. The roller is driven by a motor, through gears and/or a belt, and the roller is often cylindrical and made of a synthetic rubber or other high-friction, low-scratch-quotient material.
A disk guide guides the disk while the roller drives or rolls the disk. In order for the roller to make a friction contact with the disk, the roller is sometimes made of a soft, spongy material, or various arrangements of pivots or springs may be employed to press the roller and disk guide together, with the disk between the roller and the disk guide.